strike point

[A440A@aol.com]

       The strike point is determined, (not designed),  by the placement of
the action, the angle the hammer is installed on the shank, and the length of
the boring.
      Some pianos ,in the top section ,have the string rising up from capo
bar to the bridge at such angle that hanging angle AND bore distance must
both be used in order to bring the angle of attack to 90 degrees.
      In these situations, having the  hammer contact the string at ninety
degrees is not possible by altering just the bore distance, ( with extremely
short bore distances, you often run into regulation problems concerning the
let-off buttons and stop screws, not to mention the alteration of the arc
coincidence of jack and knuckle).
     If hammer 88 is leaned proximally  in order to improve its angle of
attack, the distance it must be hung out on the shank will have to be
increased to keep the strike point the same.  There is often room for the
attendant back-check alteration in this part of the piano, though lower down
will at times cause problems with Sostenueto rods.

Just a few thoughts.
regards
Ed Foote